Water heater



J. J. FISCHER Dec. 13, 1966 WATER HEATER 2 Sheets-Sheet 1 Filed Jan. 27, 1964 IN VEN TOR.

JOHN J FISCHER BY.

A TTORN E YS.

Dec. 13, 1966 J. J. FISCHER 3,291,103

WATER HEATER Filed Jan. 27, 1964 2 Sheets-Sheet 2 INVENTOR.

JOHN J. FISCHER A TTOANE VS.

United States Patent 3,291,103 WATER HEATER John J. Fischer, East Stroudshurg, Pa., assignor to The Patterson-Kelley Co. Inn, East Stroudsburg, Pa. Filed Jan. 27, 1964-, Ser. No. 340,348 Claims. (Cl. 12233) This invention relates to industrial Water heaters, and more particularly to an improved indirect type water heater wherein the intermediate water heating fluid circulates through tubes enclosed within a heating duct; said tubes having external fins running longitudinally thereof for absorbing heat from hot gases flowing along the outer surfaces of the tubes and the fins; the duct leading from the combustion chamber to the stack.

Whereas such tubes are usually bundled and enclosed within a cylindrical duct or wrapper conveying the heating gases to the stack, as from a gas or oil burner or the like; it is an object of the present invention to provide a water heater arrangement embodying an improved tube bundling and Wrapper system, whereby the tubes are disposed in an improved sectionally nested relation, and are enclosed within an improved form of wrapper sheet which closely conforms to the peripheral configuration of the tube bundle.

Another object is to provide an improved hot gas entrance arrangement in connection with bundled tube systems as aforesaid, whereby the heating gases are guided to how longitudinally of the tubes and throughout the length of the bundle wrapper in intimate scrubbing relation with the tube walls and fins, without opportunity to bypass into offside spaces unoccupied by tubes, such as in the case of the prior art. Thus, it is a primary object of the invention to provide a heat exchange arrangement of the type referred to which provides increased heat exchange efficiency.

Other objects and advantages of the invention will appear from the specification hereinafter and the accompanying drawing, wherein:

FIG. 1 is a side elevational view, partly in section, of an indirect type water heater embodying the invention;

FIG. 2 is a section, on enlarged scale, taken along line IIII of FIG. 1; and

FIG. 3 is a front end view of the heater of FIG. 1.

As illustrated by way of example herein, the invention is embodied in a water heater of the horizontal tube, gas or oil burning type, generally self-contained within a water storage tank 10. For convenience in handling such equipment is usually carried on skids as shown at 12. A gas burner unit as illustrated at 14 may be mounted directly on the front end of the tank to project a flame into the combustion chamber front end of a hot gas tube 16 which runs through the length of the tank and discharges into a stack or flue as indicated at 18. A bundle of return bent water tubes as indicated at 20 is disposed in the rear end portion of the hot gas cylinder 16; each tube 20 being externally and longitudinally finned as indicated at 22 (FIG. 2).

As shown herein, the tubes 20 communicate through a tube sheet 24 into a dual bonnet 26 which in turn communicates through a pair of conduits 28 and a circulating pump 29 with a second bonnet 30. Thus, the system is arranged to deliver in closed circuit manner a soft or mineral-free water supply to a second tube bundle 32 which is immersed in the cold raw water section of the tank 10, for indirect heating of the water entering and temporarily stored in the tank as from the cold water inlet 31. The heated water outlet is indicated at 33 and thus it will be understood that raw cold water entering the tank 10 through inlet 31 first comes in heatexchange con-tact with the tubes 32 containing tluid heated 3,291,1ifi3 Patented Dec. 13, 1966 by the tubes 20, then passes upwardly and around the duct 16 into the upper part of the tank where it is stored until drawn out of the outlet 33. By virtue of this closed circuit intermediate (chemically pure) fluid circulating arrangement, high metals temperatures are avoided in associa-tion with the raw watercontacted surfaces of the system. Hence, the system is adapted to operate in scale-free manner even though relatively hard waters are being handled.

The present invention features also a sectionally compact nesting of the heating tubes 20 as shown best in FIG. 2, as well as a novel wrapper sheet arrangement for the tube bundle as illustrated at 34. Instead of being of conventional cylindrical form, the wrapper 34 is shaped to intimately conform to the sectional profile of the tube bundle, whereby interiorly of the wrapper the hot gas travel spaces between the tubes and the wrapper are of substantially equal sectional areas. Hence, the .hot gases are thereby confined to travel lengthwise of the tubes (along and between the fins thereof) in intimately scrubbing relation with the tube walls and fins. No side- Wise open spaces exist into which the relatively low pressure hot gases can bypass and set up unequal gas travel conditions with consequent heat exchange in inefiiciencies. To further enhance this etfec-t, the wrapper 34 adjacent the front end of the enclosed tube bundle is fitted With an external flange 36 which closes the entrance to the space between the wrapper 34 and the hot gas cylinder 16, thereby enforcing travel of all heating gases through the interior of the wrapper 34 and along the water tubes and their fins as explained hereinabove.

It will therefore be appreciated that in the case of the water heater of the present invention the heating gases will all be confined to pass in improved scrubbing manner against the heat-exchange tubes 20 and fins 22, and that the compact arrangement of the finned surfaces greatly reduces the requisite size of the hot gas heat transfer system; thereby providing substantial heat-exchange efiiciency improvement. At the same time the indirect intermediary fluid circulation system precludes the development of temperatures in association with the raw water supply; thereby making the system of the invention practicable substantially scale-free and productive of increased efficiencies in the water heating industry. Also, it will of course be understood that the features of the invention may be embodied with equal facility in connection with a variety of water heater types; and that although only one specific form of the invention has been illustrated and described in detail herein by way of example, various changes may be made therein without departing from the spirit of the invention or the scope of the following claims.

I claim:

1. A water heater comprising in combination,

a temporary storage and heating tank having a cold water inlet into the bottom thereof and a hot water outlet at the top thereof,

a heating gas duct extending horizontally through said tank at an intermediate elevation thereof,

means delivering hot gases into one end of said duct and stack means in communication with the other end of said duct,

a first heating tube bundle and wrapper unit disposed within said duct intermediately of its ends,

said unit comprising a first bundle of return bent fluidcarrying tubes extending from a tube sheet enclosed by a first bonnet, and a Wrapper member,

said first tubes being disposed in a sectionally nested relationship defining plural rows and layers of tubes when viewed endwise, the tubes of alternate layers being disposed in staggered inter-nesting relationship and said wrapper member comprising a hot gas carrying conduit enclosing said tubes and sectionally profiled to conform closely to the perimeter profile shape of said tube bundle, thereby providing gas passageways through said wrapper and around and between said tubes of substantially equal sectional areas,

baflle means at the gas inlet end of said wrapper spanning the space between said wrapper and said gas duct to force all gas flow to travel through said Wrapper, and said wrapper being open at its other end to deliver spent gases to said stack,

and an intermediate fluid heating and circulating system comprising a second bundle of heating tubes disposed within the lower portion of said tank and connected in communication with a second bonnet, said first and second bonnets being intercommunicated by a dual conduit and circulating pump system, said first and second tubes and bonnets and intercommunicating conduit and pump devices comprising a closed circulation system containing a scale-free fluid,

where hot gases delivered into said gas duct pass through said wrapper in intimate heat-exchange scrubbing manner against said first tubes and thence to said stack, while said pump circulates the fluid within said tubes in heat-exchange relation therewith, thereby transferring heat from the gases to the water in the lower portion of said tank.

2. A water heater comprising in combination,

a temporary storage and heating tank having a cold water inlet and a hot water outlet,

a heating gas duct extending horizontally through said tank at an intermediate elevation therof,

means delivering hot gases into one end of said duct and stack means in communication with the other end of said duct,

a heating tube bundle and wrapper unit disposed within said duct intermediately of its ends,

said unit comprising a bundle of return bent fluid-carrying tubes extending from a fluid inlet-outlet bonnet, and a wrapper member,

said tubes being disposed in a sectionally nested relationship defining plural rpws and layers of tubes when viewed endwise, the tubes of alternate layers being disposed in staggered inter-nesting relationship and said wrapper member comprising a hot gas carrying conduit enclosing said tubes and sectionally profiled to conform closely to the perimetral profile shape of said tube bundle, thereby providing gas passageways through said wrapper and around and between said tubes of substantially equal sectional areas,

bafiie means at the gas inlet end of said wrapper spanning the space between said wrapper and said gas duct to force all gas flow to travel through said wrapper, and said wrapper being open at its other end to deliver spent gases to said stack,

and an intermediate fluid heating and circulating system comprising a heat exchange device disposed within the lower portion of said tank and connected in communication by a conduit and circulating pump system with said tubes whereby said tubes and intercommunicating conduit and pump devices comprise a closed circulation system containing a scale-free fluid,

and whereby hot gases delivered into said gas duct pass through said wrapper in intimate heat-exchange scrubbing manner against said tubes and thence to said stack, while said pump circulates the fluid within said tubes in heat-exchange relation therewith, thereby transferring heat from the gases to the water in the lower portion of said tank.

3. A water heater comprising in combination,

a temporary storage and heating tank having a raw water inlet and a hot water outlet,

a heating gas duct extending horizontally into said tank at an intermediate elevation thereof,

means delivering hot gases into one end of said duct and stack means in communication with the other end of said duct,

a heating tube bundle and wrapper unit disposed within said duct intermediately of its ends,

said unit comprising a bundle of fluid-carrying tubes and a wrapper member,

said tubes being disposed in a sectionally nested relationship defining within said wrapper plural rows and layers of tubes when viewed endwise, the tubes of alternate layers being disposed in staggered internesting relationship,

said wrapper member comprising a hot gas carrying conduit enclosing said tubes and hexagonally profiled sectionally to conform closely to the perimetral profile shape of said tube bundle, thereby providing gas passageways through said wrapper and around and between said tubes of substantially equal sectional areas,

bafiie means at the gas inlet end of said wrapper spanning the space between said wrapper and said gas duct to force all gas flow to travel through said wrapper, and said wrapper being open at its other end to deliver spent gases to said stack,

and an intermediate fluid heating and circulating system comprising a heat exchange device disposed within the lower portion of said tank and connected in communication by a conduit and circulating pump system with said tubes whereby said tubes and intercornmunicating conduit and pump devices comprise a closed circulation system containing a scale-free fluid,

and whereby hot gases delivered into said gas duct pass through said wrapper in intimate heat-exchange scrubbing manner against said tubes and thence to said stack, while said pump circulates the fluid within said tubes in heat-exchange relation therewith, thereby transferring heat from the gases to the water in the lower portion of said tank.

4. A water heater comprising, in combination,

a temporary storage and heating tank having a cold water inlet and a hot water outlet,

a heating gas duct disposed within said tank,

means for delivering hot gases into one end of said duct and stack means in communication with the other end of said duct,

means for extracting the major heat content of the gases passing through said duct to minimize direct transfer of heat from the hot gases to the water within the tank, the heat extracting means including a first tube bundle disposed within said duct and directly contacted by the hot gases therein,

means for heating the water in said tank comprising a second tube bundle within said tank exterior to said duct,

a scale-free fluid filling said first and second tube bundles,

means forming a closed path between said first and second tube bundle for circulating the scale-free fluid,

a wrapper surrounding said first tube bundle and spaced inwardly of said duct, and bafiie means at the gas inlet of said wrapper spanning the space between said wrapper and said duct to force the gases to flow through said wrapper, and said wrapper being open at its other end to deliver spent gases to said stack means.

5. A water heater assembly comprising, in combination,

an elongate water tank,

a duct extending longitudinally and substantially cen trally through said tank,

means at one end of said tank for delivering hot gases through said duct and a stack mechanism at the other 5 6 end of the tank for discharging hot gases emanating References Cited by the Examiner from the other end of said duct, UNITED STATES PATENTS a first tube bundle projecting into said duct from said 44,153 9/1864 Bayley 12233 a ge i r icf tib s l iii idle parallel to but offset from said 1768058 6/1930 Hartmann 122 33 X 3,083,763 4/1963 Brown 165159 duct and pro ecting 1nto said tank from said other end thereof FOREIGN PATENTS means for circulating a scale-free fluid in a closed path 721,65 8 12/1931 F serially between said tube bundles, 673,897 3/1939 Germany. said tank having a cold Water inlet adjacent the entrance 10 448,962 6/ 1936 Great Britain.

of said second tube bundle into said other end of the 259,071 7/ 1928 Italy.

tank, and a hot Water outlet disposed diagonally of the inlet and adjacent said one end of the tank. KENNETH SPRAGUE Pnmmy Examiner 

4. A WATER HEATER COMPRISING, IN COMBINATION, A TEMPORARY STORAGE AND HEATING TANK HAVING A COLD WATER INLET AND A HOT WATER OUTLET, A HEATING GAS DUCT DISPOSED WITHIN SAID TANK, MEANS FOR DELIVERING HOT GASES INTO ONE END OF SAID DUCT AND STACK MEANS IN COMMUNICATION WITH THE OTHER END OF SAID DUCT, MEANS FOR EXTRACTING THE MAJOR HEAT CONTENT OF THE GASES PASSING THROUGH SAID DUCT TO MINIMIZE DIRECT TRANSFER OF HEAT FROM THE HOT GASES TO THE WATER WITHIN THE TANK, THE HEAT EXTRACTING MEANS INCLUDING A FIRST TUBE BUNDLE DISPOSED WITHIN SAID DUCT AND DIRECTLY CONTACTED BY THE HOT GASES THEREIN, MEANS FOR HEATING THE WATER IN SAID TANK COMPRISING A SECOND TUBE BUNDLE WITHIN SAID TANK EXTERIOR TO SAID DUCT, 